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Field and Forage Crops |
In North Carolina, different cotton pests demand different control approaches, ranging from a high reliance on biological control for cotton aphids, through a dependence on careful scouting assessments for bollworms and stink bugs and their damage, and finally in utilizing a preventative, at-planting preemptive strike for our soon-to-arrive thrips. Thrips have been such a consistent, recurring problem in the Carolinas and in Virginia that insecticidal control is not a matter of if to treat, but only of what at-planting approach is taken (i.e., seed treatment versus an at-planting insecticide).
With cotton planting now underway and with most of our crop hopefully in the ground by May 10, virtually all cotton producers have already decided on their thrips management approach. Most have decided on 4 to 5 pounds of Temik 15G, although seed treatments such as Cruiser and Gaucho Grande have gained greater grower acceptance during the past few years.
With adequate soil moisture for Temik activation, this product at the 5 pound rate has constantly provided good thrips control for 4 to 5 weeks. Another advantage of this product is its activity against our common nematodes when used at rates in the 5 to 7 pound range. However, if soil moisture is low, thrips scouting can be a bit trickier following Temik than with seed treatments that are sprayed with a foliar insecticide at the first true leaf stage. These foliar treatments are not dependent on soil moisture to be effective, and are often well timed with an early Roundup, another glyphosate, or Ignite herbicide application as a tank mix.
Although seed treatments are convenient, safe, and somewhat less costly than Temik, they seldom show thrips activity beyond about three weeks after planting. For cotton planted in the typical late April to May 10 window, three weeks after planting is often a time of high thrips activity and a foliar application is recommended. For cotton planted around May 15 to May 20 or later (because of the cotton plants' rapid growth under warmer conditions and the often lower invading thrips populations), a foliar spray following seed treatments may often be avoided. Temik at a rate of 3 pounds per acre will also often provide adequate thrips control at this time.
Although the foliar applications often used following seed treatments are typically organophosphate insecticides (such as Orthene) which may cause cotton aphid and/or tobacco budworm outbreaks, in reality the aphid activity of the chloronicotinoid seed treatments themselves often extends well beyond the three week thrips activity window, and budworms do not become established on Bollgard and Widestrike cotton lines, which are now used on almost 85 percent of North Carolina's cotton acreage.
Cereal leaf beetle populations have been observed to be slower to develop so far this spring in the Piedmont areas of North Carolina. Populations are lower and later than last year to this point. This appears particularly true in plots that were not planted in small grains last year. The North Carolina Department of Agriculture and Consumer Service's test plots are reporting a higher incidence of larval parasitism.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on April 25, 2005 by Stephen J. Toth, Jr.